Shutoff Control Method for Power Conversion Interlock Systems

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Solution Overview

Problem

Existing interlock control mechanisms require complex manual operations for canceling interlock functions and do not address abnormal manipulations or failures, lacking a comprehensive solution for double assembly scenarios.

Innovation Solution

A shutoff control method that determines the status of a device based on two signals, outputting a shutoff signal when both signals match a predetermined status, entering a cancellation status, and canceling the shutoff without a reset process, while providing warnings for abnormal conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a cancel switch is installed to cancel interlock operation, then the interlock function can be canceled, but the operation becomes complicated and requires additional components

Engineering Contradiction:
Improveinterlock functionVSAvoidcancellation operation
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent extracts the cancel switch function from the physical circuit and implements it as a software flag (cancellation flag) in the control unit. This eliminates the need for a separate physical cancel switch component while maintaining the interlock cancellation functionality through digital logic operations.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a control unit as an intermediary between the door switch and the power source switching device. The control unit processes door switch signals, manages interlock status through internal flags, and controls the power source switching device, thereby simplifying the overall operation and eliminating the need for separate cancel switches.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a cancel switch is installed to cancel interlock operation, then the interlock function can be canceled, but additional components and complex wiring are required

Engineering Contradiction:
Improveinterlock functionVSAvoidinterlock circuit
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the interlock control function and the cancel function into a single control unit. The control unit integrates door switch signal processing, interlock status management, and power source switching control, thereby eliminating the need for separate cancel switches and reducing circuit complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the cancel switch functionality from the hardware circuit and implements it as a software-based flag system within the control unit. This conversion from hardware to software implementation reduces the number of physical components and simplifies the interlock circuit.

Inventive Principle:
Principle #2Taking out (Extraction)

3Device complexity

If only a single door switch is used, then the circuit is simple, but failures or abnormal manipulations cannot be detected

Engineering Contradiction:
Improveswitch circuitVSAvoidinterlock control
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies different quality requirements to different parts of the control system. The control unit performs enhanced monitoring and diagnostic functions on the door switch signals, while the door switches themselves remain simple. This localized enhancement of monitoring capability improves reliability without significantly increasing overall system complexity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The control unit continuously monitors door switch signals and provides feedback on the interlock status. It detects abnormal manipulations and potential failures by analyzing signal transitions and maintaining status flags, thereby improving reliability through active monitoring without requiring additional physical switches.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3327883B1Shutoff control method and power conversion device using same
Publication Date: 2020.09.09 HITACHI IND EQUIP SYST CO LTD
  • EP3327883B1 patent drawingFigure 1
  • EP3327883B1 patent drawingFigure 2
  • EP3327883B1 patent drawingFigure 3~4

AI summary

In order to address the issue of providing a system whereby, if a malfunction occurs during interlock control, interlocking occurs safely and a warning is provided to an operator, this shutoff control method determines the shutoff state of a device on the basis of a transition state of two signals and comprises: a first step in which a shutoff signal is output to the device if the two signals fulfil a predetermined shutoff state; a second step in which, after the states of the two signals have both reached the predetermined shutoff state, both of the two signals are changed to a predetermined shutoff release state; and a third step in which the shutoff state of the device is released and the device is started without being reset. As a result, warnings can be provided when malfunctions occur, without complicated work during normal operation of functions.